The present invention relates to a resin intake manifold for distributing intake air through a throttle body of a multi-cylinder internal combustion engine of an automobile, etc., or a gaseous mixture of air and fuel into different cylinders of the multi-cylinder internal combustion engine, and a manufacturing process of such a resin intake manifold.
The conventional choice of intake manifold is an intake manifold made of resin (resin intake manifold), chiefly due to its superior properties providing good insulation, lightweight, and more freedom in terms of shape. The resin intake manifold includes a chamber section having an intake port which opens into a throttle body, and a plurality of pipe sections which connect interior of the chamber section to the respective cylinder of a multi-cylinder internal combustion engine. The configuration of the resin intake manifold is generally complex and its manufacturing process generally involves splitting the resin intake manifold into a plurality of half-parts and later joining them in a post-process. In this case, in order to reduce the number of divisions of the resin intake manifold, a slide mechanism which can form a plurality of pipe sections at once has been known.
{circle around (1)} Japanese Unexamined Patent Publication No. 166875/1995 (Tokukaihei 7-166875) (published date: Jun. 27, 1995) and {circle around (2)} Japanese Unexamined Patent Publication No. 231760/1998 (Tokukaihei 10-231760) (published date: Sep. 2, 1998) disclose a resin intake manifold which has an opening, leading to a throttle body, at one end of the chamber, and a plurality of pipes which are lined and integrated with the chamber. Further, {circle around (3)} Japanese Unexamined Patent Publication No. 196373/1998 (Tokukaihei 10-196373) (published date: Jul. 28, 1998) and {circle around (4)} Japanese Unexamined Patent Publication No. 299591/1998 (Tokukaihei 10-299591) (published date: Nov. 10, 1998) disclose a resin intake manifold in which an opening leading to a throttle body is provided at a center of the chamber.
The resin intake manifolds of the foregoing publications {circle around (1)} through {circle around (4)} all have complex configurations, which force them to employ a manufacturing method using the slide mechanism which can create complex shapes with a small number of divisions.
However, with conventional methods using the slide mechanism, the resin intake manifold is formed by design, for example, from two or three divided parts, and this requires a mold with a large manufacturing cost. Thus, when the number of intake manifolds manufactured is small, the manufacturing cost per product is increased. Further, manufacturing methods using the slide mechanism require the pipes to be provided inside the chamber, which necessitates the use of an additional member, a partition wall, which is provided separately from a mold. The partition wall has a complex fitting structure, and causes the problem of flat areas in the inner wall surface of the pipe sections.
That is, resin intake manifolds generally have complex configurations, and to reduce the number of divisions, the slide mechanism has been used conventionally. However, manufacturing methods using the slide mechanism have problems that 1) it requires a large and expensive mold and the manufacturing cost per product is increased when the number of products manufactured is small, 2) the partition wall used to provide the pipe sections has a complex fitting structure, and 3) flat areas are formed in the inner wall surface of the pipe sections.
The present invention was made in view of the foregoing problems, and its object is to provide a resin intake manifold which can be manufactured at low cost even when the number of products manufactured is small, and a manufacturing process of such a resin intake manifold.
In the present invention, as the term is used herein, xe2x80x9cresinxe2x80x9d refers to those molding materials which can flow into a mold when melted to become a molten material at a high temperature, and which become sufficiently strong when solidify. Accordingly, the resin used in the present invention is not just limited to so-called polymer resins such as plastic.
In order to achieve this object, a resin intake manifold of the present invention includes a chamber section with an intake port which leads to a throttle body, and a plurality of pipe sections which connect interior of the chamber section to respective cylinders of a multi-cylinder internal combustion engine, wherein: the chamber section comprises a cylinder body which is made up of a plurality of port members coupled together, each of the plurality of port members having a pipe section, and a cylindrical section whose external wall is connected to one end of the pipe section.
The chamber section of the resin intake manifold of the present invention comprises a cylinder body which is made up of a plurality of port members coupled together, each of the plurality of port members having a pipe section, and a cylindrical section whose external wall is connected to one end of the pipe section. That is, the resin intake manifold is divided into the port members which can be manufactured using a small mold of a low cost of production. As a result, less cost is required for the mold, which allows the resin intake manifold to be manufactured at low cost even when the number of products manufactured is small.
The port members may be provided, for example, as a cast of half-parts. That is, the port members can be provided without using the slide mechanism, and therefore do not require the use of the partition wall having a complex fitting structure. This prevents areas of flat portions in the inner wall of the pipe section.
Further, by changing the number of port members of the chamber section, the product resin intake manifold can adapt to engines with various numbers of cylinders, provided that the cylinders of the engine have substantially the same displacement. That is, the port member can be used as a common member to manufacture a resin intake manifold which can adapt to engines with various numbers of cylinders. Thus, manufacturing cost of resin intake manifolds can be reduced.
In the present invention, xe2x80x9cchamber sectionxe2x80x9d refers to a hollow portion of a section whose external wall is connected to one end of the pipe section, and, for example, it is formed by coupling the cylindrical body which is made up of the plurality of port members coupled together, a throttle body mounting pipe member, and a lid section which closes an end or both ends of the cylindrical body. Note that, the cylindrical body may alternatively comprise the plurality of port members coupled to a cylindrical member which is provided with an intake port and inserted between any of the port members. The shape of the chamber section, which is not particularly limited, is cylindrical, for example.
The resin intake manifold of the present invention may have an arrangement wherein the pipe section extends out of the chamber section to coil along the external wall of the chamber section, and at least a portion of the external wall of the pipe section on the side of the external wall of the chamber section is connected to the external wall of the chamber section.
With this arrangement, the air space of gap between the pipe section and the chamber section can be eliminated, thus making the resin intake manifold compact.
In addition, rigidity of the chamber section can be improved. Thus, for example, even when the chamber section is under high pressure due to a backfire, etc., the pressure can be dispersed over the pipe section through the connected portion, thus preventing damage to the chamber section.
The resin intake manifold of the present invention may have an arrangement wherein an opening portion of the pipe section on the side of the chamber section is in the form of a funnel.
With this arrangement, gas flows more smoothly from the chamber section to the pipe section, thus improving suction efficiency of the pipe section. According to this arrangement, the funnel is integrated as a portion of the pipe section when forming the port member. This makes the inner wall of the opening portion in the form of a funnel smoother than that of the funnel which is separately provided later to the opening end of the pipe section. As a result, gas flows more smoothly from the chamber section to the pipe section, thereby further improving suction efficiency of the pipe section.
The resin intake manifold of the present invention may have an arrangement wherein: the chamber section comprises a cylindrical body which is made up of the plurality of port members coupled to a cylindrical member which is provided with an intake port and inserted between any of the port members, and the pipe section is curved to coil along an external wall of the chamber section, and is bent toward the intake port.
With this arrangement, the resin intake manifold can be made more compact while ensuring sufficient length for the pipe section.
The resin intake manifold of the present invention is preferably manufactured by the steps of: forming the port member having the pipe section and the cylindrical section whose external wall is connected to one end of the pipe section; and forming the cylindrical body which is made up of the plurality of port members coupled together.
This method allows the port members to be manufactured using a small mold, thus manufacturing the resin intake manifold at low production cost even when the number of products manufactured is small.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.